1. Field of the Invention
This invention relates generally to valves. More particularly, the invention relates to valves having multiple ports.
2. Description of Related Art
Valve assemblies having multiple ports have existed for many years and have been used in a wide variety of applications. One such application is the use in dental medicine. A device known as a tooth de-scaler is used to remove plaque build-up on teeth. The device uses ultrasonic waves to effectuate the plaque removal.
While the device is being used, a stream of fluid is drawn into a small hose attached to the tip of the de-scaling device where the fluid exits. The fluid is used to wash away any loosened plaque. Such tooth de-scaling devices are designed to allow for three different fluid options. One option is regular tap water. A second option is bi-carbonate water. A third option is fluoride-fortified water.
Selection of the fluid source is accomplished by a multi-port valve which is required to handle pressures of approximately 65 psi which is a typical pressure at which tooth de-scaling devices are operated. The need to be able to shift quickly from one fluid option to another poses a number of problems.
One problem relates to the leakage of air from the multi-port valve. This is a problem that is common to most multi-valves. The key is to limit the leakage to less than one bubble per second to achieve what is known as “bubble tight” operation when the valve ports are plugged and the valve is submerged and pressurized. Some designs, for example, a conical valve and conical valve seat design does not sufficiently seal to minimize bubble production. As a result, an undesirable hissing sound emanates from such a valve assembly when exposed to fluid pressures in the 65 psi range.
It is therefore an object of the invention to provide a multi-port valve system that can minimize air leakage to no more than one bubble per second. Another object of the invention is to provide a valve having a “miniature envelope” which meets or exceeds the criteria to receive UL approval.
A still further object of the invention is to provide a bearing system that allows for effortless, maintenance-free rotation of the valve rotor within the valve housing.